1. Field of the Invention
The invention relates to a checking method in which serial data protected by means of check data are transmitted via a serial data bus from a transmitter to a receiver, to an electronic transmission or reception circuit or to a transceiver, which comprises a transmitter and a receiver having serial data transmission means and to the use thereof.
2. Description of the Related Art
Serial bus systems, such as “Controller Area Network” (CAN), Flexray(R) or “Serial Peripheral Interface” (SPI), are already used in motor vehicle electronics for the purpose of networking electronic controllers or micro-controllers. A common feature of these serial bus systems is that the data to be transmitted are split into data telegrams (frames). Each data telegram has a CRC (Cyclic Redundancy Check) checksum, calculated on the basis of a generator polynomial, appended to it. The CRC check on data is known per se, inter alia from DE 41 30 907 A1, EP 1 763 168 A1, DE 33 35 397 A1 or WO 2006/058050 A2.
WO 2006/058050 A2 discloses a CRC error recognition system in which CRC data (CRC corrupters) are manipulated. The manipulation is performed in order to produce a particular synchronization condition or to transmit particular status information to the receiver. This has the disadvantage that the CRC check is not active at least when some data packets are transmitted. The security of the transmission is therefore reduced. A further drawback is that an actual error in the CRC data can, in principle, trigger an unwanted synchronization event.
The means for producing the CRC check data are known to be generally implemented as hardware means. The result of protecting the data using conventional CRC check data is that one hundred percent data protection is not attained. The residual error that remains can be calculated or estimated for a prescribed length of data telegrams either analytically or by means of simulations.
EP 1 763 168 A1, already mentioned further above, proposes reducing the residual error by forming a second CRC protection attachment.